Meet Dale — our free AI heating expert. Ask him about fault codes, cold radiators, leaks or pressure drops and get a plain-English answer in seconds.
Type a fault code, a symptom or a question. Dale explains what's likely wrong, what's safe to try yourself, and when to book a Gas Safe engineer.
Recognise the symptom, understand the likely cause and know what's safe to try before calling a Gas Safe engineer.
Symptom · Boiler powered on but radiators and taps stay cold.
Likely cause · Failed diverter valve, seized pump, faulty thermostat, low pressure or a blocked condensate pipe (in cold weather).
What to do · Check pressure (1–1.5 bar), thermostat batteries and time clock. If it's frozen weather, thaw the white plastic condensate pipe outside.
Symptom · Pressure gauge drops below 1 bar and boiler shuts down.
Likely cause · Leak on radiator valves, pipework or a failed expansion vessel inside the boiler.
What to do · Top up via the filling loop to 1.2 bar. If it drops again within days, book a repair — a slow leak damages floors and ceilings.
Symptom · Top of radiator is hot, bottom stays cold. Some radiators don't heat at all.
Likely cause · Sludge — magnetite build-up sitting in the bottom of radiators. Reduces efficiency and shortens boiler life.
What to do · A powerflush clears the system. Book a survey; we'll confirm if a powerflush or a magnetic filter fit is right.
Symptom · Water dripping from the base of the boiler or damp patches under it.
Likely cause · Failed pump seal, corroded heat exchanger, over-pressurised system or loose fittings.
What to do · Turn off the boiler and water supply, catch the drip and book a Gas Safe engineer. Don't top up the pressure — that makes it worse.
Symptom · Loud rumbling, banging or a kettle-like whistle from the boiler.
Likely cause · Limescale or sludge on the heat exchanger causing water to boil in localised spots.
What to do · Usually fixed by a powerflush plus a scale reducer. Ignoring it damages the heat exchanger — an expensive part.
Symptom · You turn the stat up, boiler doesn't fire.
Likely cause · Flat batteries, lost wireless pairing, broken wiring or a failed programmer.
What to do · Replace batteries first, then re-pair the receiver. If that doesn't fix it, we can fit a smart replacement.
The codes we see most across Worcester, Vaillant, Ideal, Baxi and Glow-worm boilers in Brighton & Hove homes.
Ignition lockout — boiler can't detect a flame.
Check gas supply is on and pressure is 1–1.5 bar. Reset once; if it recurs, book a repair.
Overheat — safety thermostat has tripped.
Do not keep resetting. Usually a pump, sensor or blocked system issue — needs an engineer.
Low water pressure warning.
Top up via the filling loop to 1.2 bar. If it drops again quickly, you likely have a leak.
Low water pressure in the system.
Repressurise to 1.0–1.5 bar cold. Repeated drops = leak or failed expansion vessel.
Ignition failure — no flame on start-up.
Check gas is on and other gas appliances work. Reset once; call an engineer if it returns.
Pump or pressure sensor fault.
Common on older Ecotecs — usually a stuck pump or faulty sensor. Needs a Gas Safe engineer.
Ignition lockout.
Confirm gas supply, reset once. Persistent L2 = ignition lead, gas valve or PCB.
Low system pressure.
Top up via the filling loop. Look for damp patches on pipework and radiator valves.
Ignition failure / gas supply issue.
Check gas is on, meter isn't tripped. Reset once. Recurring E133 needs an engineer.
Low water pressure.
Repressurise to 1.2 bar. Bleed radiators and top up again if pressure drops.
Low water pressure.
Repressurise cold to 1.0–1.5 bar. Check for weeping valves and radiator leaks.
Ignition failure after multiple attempts.
Check gas supply. Persistent F9 usually means gas valve, electrode or PCB.
Don't see your code? or contact us.
Smell gas or hear a hiss?
Call the National Gas Emergency line — 0800 111 999
Open doors and windows, don't switch anything electrical on or off, and leave the property.
One reset is fine. If the same code comes back, stop resetting — you can damage components. Book a Gas Safe engineer instead.
Not immediately dangerous, but it means there's a leak somewhere. Left alone it can damage floors, ceilings and eventually the boiler itself.
Modern sealed systems run at 1.0–1.5 bar cold. Below 0.5 bar and the boiler shuts down for safety. Top up via the filling loop under the boiler.
Sludge — black magnetite from corroded steel — sits at the bottom of radiators. A powerflush and a magnetic filter clear it and protect the new boiler.
You can top up pressure, bleed radiators, and change thermostat batteries. Anything involving the burner, gas or internal components must be done by a Gas Safe engineer (reg 204352).
Diagnostics are a fixed call-out fee, then parts + labour quoted before we start. Most common repairs are done same-day.
Gas Safe registered engineers in Brighton & Hove. Fixed diagnostic fee, transparent pricing, most repairs done same-day.
